Conventionally, various projector-type headlights have been proposed, such as those disclosed in Japanese Patent No. 4080780 (or U.S. Application Publication No. 2003/0198060A1 or EP1357332A2 corresponding thereto).
FIGS. 1A and 1B are a vertical cross-sectional view of a projector-type vehicle headlight 200 described in the above publication and a top plan view thereof, respectively.
As shown in FIG. 1A, the projector-type vehicle light 200 can include a projection lens 230 having an optical axis AX1, a light source 210 disposed on the optical axis AX1, and a reflector 220 having a reflecting surface 220a formed thereinside above the light source 210. Light emitted from the light source 210 can be reflected by the reflector 220 (reflecting surface 220a) forward to be gathered close to the optical axis AX1, and the reflected light can be projected through the projection lens 230 disposed in front of the reflector 220, whereby the light can be projected forward of the vehicle headlight. Herein, the projection lens 230 can have a convex light emitting surface 232 and a plane light incident surface 234 so as to be configured as a plano-convex lens in a rotationally symmetric shape. (See FIGS. 1A and 1B.) Herein, the reflector 220 (reflecting surface 220a) can have an optical axis AX2 that is coincident with the optical axis AX1 of the projection lens 230.
With the projector-type vehicle headlight 200 with the above configuration, the light emitted from the light source 210 and projected forward through the projection lens 230 can be diffused uniformly in the right and left directions with respect to the optical axis AX1 of the projection lens 230. (See FIG. 1B.)
In the projector-type vehicle headlight 200 with the above configuration, there is a demand to utilize a rotationally asymmetric projection lens for the projector-type vehicle headlight 200, having a light emitting surface (232) inclined with respect to the optical axis AX1 of the projection lens (230) in a rotationally asymmetric manner. However, in this case, a problem would arise in which the light emitted from the light source 210 and projected forward through the projection lens (230) may be diffused locally in the right or left direction (and/or up or down direction) with respect to the optical axis AX1 of the projection lens (230).